[php-src] Issue #10889: Valgrind complaints about multiple Invalid read around fpm_event_fire()

Issue: https://github.com/php/php-src/issues/10889 Author: rcanavan ### Description While attempting to reproduce an issue in our own PHP extension, I've encountered some complaints in php-fpm by Valgrind in fpm_event_fire(). The test involved ~40 requests started at the same time with curl. I cannot reproduce this with any regularity. Sample trace: ``` Invalid read of size 8 at 0x74AA39: fpm_event_fire (fpm_events.c:483) by 0x75A6C4: fpm_event_epoll_wait (epoll.c:141) by 0x74A759: fpm_event_loop (fpm_events.c:427) by 0x743D9F: fpm_run (fpm.c:113) by 0x34BF4A: main (fpm_main.c:1813) Address 0x16c1b2c8 is 152 bytes inside a block of size 248 free'd at 0x483CA3F: free (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so) by 0x7446D0: fpm_child_free (fpm_children.c:62) by 0x7446D0: fpm_child_close (fpm_children.c:86) by 0x7446D0: fpm_children_bury (fpm_children.c:263) by 0x74A7F2: fpm_event_fire (fpm_events.c:487) by 0x74A7F2: fpm_event_loop (fpm_events.c:467) by 0x743D9F: fpm_run (fpm.c:113) by 0x34BF4A: main (fpm_main.c:1813) Block was alloc'd at at 0x483DD99: calloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so) by 0x744298: fpm_child_alloc (fpm_children.c:45) by 0x744298: fpm_resources_prepare (fpm_children.c:310) by 0x744298: fpm_children_make (fpm_children.c:399) by 0x744710: fpm_children_bury (fpm_children.c:294) by 0x74A7F2: fpm_event_fire (fpm_events.c:487) by 0x74A7F2: fpm_event_loop (fpm_events.c:467) by 0x743D9F: fpm_run (fpm.c:113) by 0x34BF4A: main (fpm_main.c:1813) ``` [fpm-valgrind.txt](https://github.com/php/php-src/files/11021655/fpm-valgrind.txt) ### PHP Version PHP 8.2.3 ### Operating System Ubuntu 22.04 (in a docker container, running on Ubuntu 22.04)